Flexible, rapid or low volume manufacturing is becoming more prevalent in many industries. A first low volume run of products will be produced and then marketed. Market feedback will be obtained, indicating that certain product modifications would be desirable, and the feedback used to modify the product for another low volume production run. This flexible or rapid manufacturing process allows manufacturers to cause their products to evolve to meet evolving user needs. Users, of course, find the responsiveness of manufacturers who have flexible manufacturing capabilities to be highly desirable.
In prototyping situations, even lower production runs can be made for the purpose of testing product designs before they are marketed. The final prototyped design can then be manufactured using flexible manufacturing low volume runs or high volume, hard tooling, production runs.
One of the important threshold design considerations, when making products from sheet material using bend-controlling slits, grooves or displacements, is the positioning and configuration of the bend-controlling structures and the positioning and configuration of the resulting bending straps between the bend-controlling structures. Thus, edge effects, stress concentrations, scrap reduction and interactions with sheet openings or structural features on the sheet all can be important design considerations that may require that changes be made to the bend-controlling slits, grooves or displacements and/or the bending straps.
The related applications set forth above disclose several techniques for manufacturing or forming bend-controlling structures that will precisely produce bending of the sheet material of these related applications, the application entitled Sheet Material with Bend Controlling Displacements and Method for Forming the Same, Ser. No. 10/795,077 is particularly pertinent in that it has an extensive disclosure as to stamping or punching processes which are particularly well suited for the economical formation of bend-controlling structures in sheet material. The bend-controlling structures of the related applications most desirably produce edge-to-face engagement of the sheet material on opposite sides of the slits for precise bending of the sheet. All of the above-identified related applications are incorporated herein by reference in their entireties.
As disclosed in the related application, bend-controlling slits, grooves or displacements can have various shapes and lengths. Moreover, the width and shape of the bending straps between longitudinally adjacent bend-controlling structures can have their configurations varied, depending upon the shape of the end portion of each bend-controlling slit, groove or displacement and the jog or transverse distance across the bend line between longitudinally adjacent slits, grooves or displacements.
As used herein, the expression “bend-controlling structures” shall mean the slits, grooves, displacements or other structures which define the bending straps extending across the desired bend line. It will be understood from the related applications, however, that the bending straps defined by the bend-controlling structures cooperate or combine with the slits, grooves or displacements to control sheet bending.
Significant economic benefits can be achieved by stamping or punching bend-controlling structures into the sheet material. The present invention seeks to reduce the stamping or punching costs further by providing die set alternatives which reduce costs and yet accommodate the various positioning and shape requirements for bend-controlling structures that will produce the desired product performance.
It is possible to employ a plurality of different stamping or punching die sets, with each die set having mating die surfaces that produce the entire bend-controlling structure. These die sets can be economically used for flexible manufacturing processes. As will be appreciated, however, an approach which is based upon a different die set for each possible slit configuration and/or bending strap width can result in an undesirably large number of punching or stamping dies sets. The present invention addresses this problem by providing several alternative solutions which reduce the cost of having a large inventory of die sets.
As part of any product design process, it is desirable for the length of the slits, grooves or displacements used to control sheet bending to be varied to accommodate the particular design. Product dimensions, for example, usually cannot be varied to accommodate slit dimensions, and particularly slit lengths. Thus, a product may have a wall which has to have a fixed width or length, and when designing the bend-controlling structures, the length of the slits, grooves or displacements producing bending of that wall is most preferably varied to accommodate the fixed wall length of the final structure. Moreover, when bend-controlling slits, grooves or displacements extend out to an edge of a sheet material, it is desirable that the bend-controlling structure does not warp, deform or cause stress concentrations at the sheet edge. For some structures this is not a difficult task, but it also is influenced by the fixed width or length of the product walls.
Possible undesirable edge effects are further complicated by the desire to minimize scrap and by the fact that the slitting, grooving and displacing techniques taught in the prior related applications are particularly well suited for relatively complex folding of sheets. Thus, sheets having a plurality of fold lines, some of which are intersecting, are common. It is not unusual, for example, for a wall of a product to end in an edge that is immediately adjacent to another wall which will be folded or bent in another direction. Accordingly, one does not want to have the bend-inducing structures for a fold line along one wall of the sheet extend over into material beyond the edge of the wall that will be folded into a different plane. Similarly, scrap is increased if slits, grooves or displacement extend outwardly of the edge of one product into an adjacent portion of the sheet which is to be used to form additional products.
Accordingly, it is an object of the present invention to provide a method of forming bend-controlling structures in a sheet of material, and the sheet of material resulting therefrom, which is particularly well suited for flexible or rapid manufacturing applications, and for prototyping, of the three-dimensional products which will result upon bending of the formed sheet of material.
Another object of the present invention is to provide a method for manufacturing products from sheet material which is well suited for use in economical stamping and punching processes employing a minimum number of indexing stations or progressive stages.
Another object of the present invention is to provide a method and set of stamping or punching dies for forming bend-controlling structures in a sheet of material which enables variation of the configuration, length and spacing of the bend-controlling structures and the intermediate bending straps using a minimum number of die sets.
Still a further object of the present invention is to provide a method for positioning bend-controlling structures in the sheet of material which will allow the slits, grooves or displacements to be positioned in the most advantageous locations relative to edges and other structural features of the end product.
Still a further object of the present invention is to provide a process and set of dies for forming bend-controlling structures in a sheet of material which minimize scrap and accommodate complex folding of the sheet into different planes.
The process for forming bend-controlling structures in a sheet of material, the resulting sheet and the die sets therefor of the present invention have other objects and features of advantage which will be set forth in more detail in, and will be more apparent from, the following Best Mode of Carrying Out the Invention, as exemplified by and illustrated in the accompanying drawing.